Julia Roberts so devastated by half-sister's death she skips Oscar lunch where she was to celebrate nomination

Julia Roberts has tirelessly been working the awards show circuit to promote her turn in August: Osage County.

But not on Monday.

The 46-year-old skipped the Academy Awards luncheon in Beverly Hills - which was attended by fellow nominees such as Sandra Bullock and Leonardo DiCaprio - to mourn the Sunday death of her half-sister Nancy Motes, 37. A rep said the entire family was 'devastated.'

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Taking a break: On Monday Julia Roberts (left) skipped the Oscar lunch in LA because of the Sunday passing of her half-sister Nancy Motes (right)

Julia, who already won a Best Actress Oscar for her turn in Erin Brockovich, has been nominated for a Best Supporting Actress award for her new drama.

On Monday, her family released a statement to People: 'It is with deep sadness that the family of Nancy Motes ... confirms that she was found dead in Los Angeles yesterday of an apparent drug overdose,' the statement read. 'There is no official report from the Coroner's office yet. The family is both shocked and devastated.'

Julia and Nancy had the same mother,
Betty Lou, but different fathers: Nancy's dad is Michael Motes and
Julia's is the late Walter Grady Roberts.

Back when: Julia is seen here stepping out with Nancy in 2006 on a cold day shopping in New York

Family: Roberts with Motes and their mother Betty Lou when the star was filming 1997's My Best Friend's Wedding

Close in the '90s: The half-sisters shared a hug when Roberts was in her 20s and the biggest star in Hollywood

Motes was discovered in the bathroom of her home by her fiancé John
Dilbeck and pronounced dead at 2:12 p.m., a spokesman for the Los Angeles Coroner's Office told MailOnline. She
is currently undergoing an autopsy to determine cause of death.
Toxicology results will likely take six to eight weeks to get back

The passing of Motes - who appeared close to her cover girl half-sibling in the '90s - poses a publicity challenge for Roberts, who has been out and about very consistently since she started promoting her new film in December.

With the Oscars three weeks off - the live show airs March 2 - the actress is supposed to make more appearances.

When and if she does, the A lister will be asked about the death of Motes. Because she is normally not keen on talking about her personal life, especially her family from Georgia, it is likely she will be put in a difficult situation.

Julia's rep did not return calls to MailOnline.

They showed up: Sandra Bullock (left), nominated for Gravity, and Leonardo DiCaprio (right), who has been given a nod for Wolf Of Wall Street, made the lunch at the Beverly Hilton Hotel that Julia was expected at

Adding to the problem is that Nancy - who was a production assistant on TV's Glee - had a bone to pick with the beauty.

In August the blonde had complained about growing up in the shadow of the Pretty Woman star. She delivering a very unflattering portrait of her Julia and their fight was not resolved publicly before the less famous sister died.

The younger sibling had said she was
known as Julia's 'fat little sister' and revealed the Oscar-winner had
taunted her about her weight, leading her to undergo weight loss surgery
in June 2012.

So much to live for: The Glee production assistant with her fiancé John Dilbeck in 2013

Still a smashing success: At 46, Roberts is more in demand than ever; here she leaves a talk about her Meryl Streep drama on February 4

On top: The actress on the February cover of Vanity Fair, on stands now

Roberts made her feel embarrassed and ashamed of
her body, according to Nancy, which peaked at 20st.

She resorted to a £20,000 gastric bypass operation last year.

'It makes me feel incredibly hurt and
very sad,' Motes said.

'When you're in a family of very, very exceptionally beautiful people it's intimidating.'

Her other siblings include Eric Roberts, 57, and Lisa Roberts Gillan,
48, who are also actors.

Actress Emma Roberts is the daughter of Eric.

'I
think that growing up as Pretty Woman's little sister has definitely
made me try to see the person inside and not the person outside,' she added. 'A lot
of my life I felt judged for my weight.'

Motes, who grew up in the US state of Georgia, was only 13 when
Roberts shot to Hollywood fame as hooker Vivian Ward in Pretty Woman.

Motes, who described herself as an 'awkward'
child who was bullied at school, could not compete with the success of
her 'very pretty and very popular' sister.

Thinner: Nancy looked considerably thinner in August 2013 as she grabbed coffee near her home in Santa Monica

She
said: 'When I was in high school and she was an adult, she would just
let me know that I was definitely overweight. She would make it quite
clear to me and in a not so nice manner.

'Julia did not want to see me go
down that path [of acting] … So I just got a lot of criticism from
Julia, which was very discouraging for me.'

After
graduating from high school in 1995, Motes auditioned for roles in Hollywood while
working as a waitress. But she could not afford to continue so returned
to Georgia.

Three years ago Nancy moved back to Los Angeles, after meeting her fiancé John
Dilbeck. But she claimed Roberts started taunting her about her
weight again days after she arrived.

Busy woman: Roberts has been working the awards circuit for her turn in August: Osage County, which she did here on January 18 while attending the Screen Actors Guild Awards

Another scene from the film Pretty Woman opposite Richard Gere, where she inspects a diamond studded necklace

With her weight soaring, she
finally decided to have a gastric bypass fitted.

Motes said she could not afford the £20,000 fee, but rather than ask Roberts, who is worth £90million, for financial help, she took out a
loan.

She had lost 7st
since the operation last June and had planned on marrying in May.

However, RadarOnline reported last year that Julia planned to boycott the nuptials because she didn't like the groom and didn't want to get stuck paying for the wedding.

'Julia doesn't think much of Nancy's husband-to-be,' the website quoted an insider as saying. 'She's convinced he's sponging off Nancy, who doesn't have much money in the first place.'

At the time of her death, it was not known if she had mended her relationship with Julia.

She
said last year: 'It's a work in progress, it's not going to be fixed overnight,
nor do I think it's going to be fixed by me just getting skinny.'

Interestingly, Julia has helped her sister Lisa who she has helped get work on her hit films Runaway Bride, Mona Lisa Smile and Eat Pray Love.

Meanwhile, Emma was spotted looking
downcast as she went out for lunch with fiancé Evan Peters in West
Hollywood on Monday, her 23rd birthday.